This invention relates to a pharmaceutical combination of compounds having analgesic activity.
U.S. Pat. No. 3,393,197 issued to Pachter and Matossian on July 16, 1968 discloses N-substituted-14-hydroxydihydronormorphines, including the N-cyclobutylmethyl derivative, commonly called nalbuphine: ##STR1## Pachter and Matossian and others, such as H. W. Elliott, et al., J. Med. (Basel), 1, 74-89 (1970); H. Blumberg, et al., Pharmacologist, 10, 189, Fall 1968; P. Roberts, Drugs of the Future, 3, 613-5 (1977), disclose the use of nalbuphine as an analgesic for the control of moderate to severe pain.
Acetaminophen, N-(4-hydroxyphenyl)acetamide, was first used in medicine by Van Mering in 1893, but only since 1949 has it gained in popularity as an effective alternative to aspirin for analgesic uses. Acetaminophen has been widely administered with a variety of other drugs, including opioid analgesics such as codeine. L. S. Goodman et al., "The Pharmacological Basis of Therapeutics," Fifth Ed., Macmillan Publishing Co., 1975, p. 348, state that it is likely that an effective dose of an opioid adds to the analgesic effect of acetaminophen as it does to that of aspirin. A. W. Pircio et al., Arch. int. Pharmacodyn., 235, 116-123 (1978), however, have reported unexpectedly enhanced analgesic action with a 1:125 mixture of butorphanol, ##STR2## and acetaminophen; whereas a similar 1:10 combination did not show statistically-significant analgesic enhancement.
More active analgesic combinations are in constant demand because they offer the attractive possibility of relieving pain with reduced dosages thereby diminishing the expected side effects and toxicity that would result from the otherwise required higher dosages.